CRR Histology Lab 5
Heart and other types of muscle
CRR Week 6
Today our emphasis is observation and appreciation of the tissue composition of the heart. A histology atlas should help
with orientation to the basic features of each slide.
The following suggestions are intended to guide your "seeing" in lab and also to prime your attention for further reading.
Please don't let your experience be limited by these exercises. On any slide, no matter how familiar, careful examination
almost always yields interesting new observations.
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Three types of muscle, Slide 15.
This slide offers isolated specimens of smooth, cardiac, and
skeletal muscle; you must figure out which is which.
Compare and contrast cardiac muscle, smooth muscle,
and skeletal muscle. Notice especially fiber diameter,
position of nuclei, size/shape of nuclei, and
presence/absence of striations (visible only in longitudinal
section).
Refer to electron micrographs (e.g., Rhodin atlas) for
informative details.
Heart, Slide 53.
Become familiar with the appearance of cardiac muscle, in
contrast to smooth and skeletal muscle fibers.
Notice especially fiber diameter, position of nuclei,
size/shape of nuclei, and presence of striations (visible only
in regions where fibers are cut longitudinally, and only at
high magnification).
Notice how individual muscle cells are attached end-toend at intercalated discs (best seen where fibers are cut
longitudinally). Intercalated discs may be dark or pale,
depending on stain.
Notice how cells branch so that myocardial tissue is
interconnected in three dimensions.
Refer to electron micrographs (e.g., Rhodin atlas) for
higher-resolution details.
Skeletal muscle, Slides 14, 29, 30.
For comparison with cardiac muscle.
Again, notice fiber diameter, position of nuclei,
size/shape of nuclei, and presence of striations (visible only
in regions where fibers are cut longitudinally, and only at
high magnification).
Smooth muscle, many slides.
For comparison with cardiac muscle. On any slide, look for
examples of smooth muscle in walls of blood vessels. Also
look for smooth muscle in slides of digestive tract
(esophagus, stomach, intestine), urinary tract (renal pelvis,
ureter, bladder), and reproductive tract (vas deferens,
Fallopian tube, uterus).
Again, notice fiber diameter, position of nuclei, and
size/shape of nuclei.
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At your discretion, you may notify an instructor
for a brief oral evaluation on this material.
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SAQ slides.
If you haven't already examined these slides, now would be
a good time. Some will look strange, but by now you
should be able to recognize some basic features on several
of these slides.
Among the nine SAQ slides are three in which muscle
comprises the bulk of the specimen. Each of these three
slides is dominated by a different type of muscle (i.e.,
smooth, cardiac, skeletal). Which ones are they?
Once you know which SAQ slide represents heart, use
your understanding of heart anatomy to determine which
portion of the specimen represents endocardium and which
is epicardium.
You should also be able to identify which SAQ slide
shows lung.
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ELECTRON MICROGRAPHS
Use Rhodin's Atlas of Histology or other electron micrographs,
online at < http://projects.galter.northwestern.edu/rhodin/ >
Find examples of muscle tissue, including skeletal muscle,
cardiac muscle, and smooth muscle. Appreciate the
banding pattern of striated muscle (A-bands, I-bands, Zlines); the presence of sarcoplasmic reticulum,
mitochondria and glycogen; and in cardiac muscle the
structure of intercalated disks.